The attack was made by a mixed force of Loyalists and Iroquois under the overall command of Mohawk leader Joseph Brant, and resulted in the destruction of houses, barns, and crops, and the taking of livestock for the raiders' use.

The settlers, warned by the heroic run of Adam Helmer, took refuge in local forts but were too militarily weak to stop the raiders.

Brant's attack was one of a series executed under his command or that of Loyalist and Seneca leaders against communities on what was then the frontier of western New York and northern Pennsylvania.

[8] When he raided settlements at Springfield and Andrustown (present-day Jordanville) in July, Brant left the survivors with warnings that German Flatts would soon also be attacked.

[17][18][19] Because of warnings received earlier that Brant was planning an attack, Colonel Bellinger had been sending out scouts in the direction of Unadilla to gather intelligence.

[22] Caldwell, Brant, and their men arrived at German Flatts not long after Helmer's warning, on the evening of September 16, and began their attack the next morning.

Captain Caldwell wrote that his men "would have in all probability killed most of the inhabitants of German Flatts had they not been apprised of our coming by one of the scouts getting in and warning of our approach, and perhaps got to their forts".

[26] Commanded by Generals John Sullivan and James Clinton, the 1779 expedition systematically destroyed the villages of Iroquois tribes fighting for the British, but did little to stop the frontier war.

[28] Walter D. Edmonds' 1936 novel Drums Along the Mohawk recounts the story of Adam Helmer's run and gives an overview of the German settlements along the river.